JP2001332603A - Substrate carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate carrier in which a substrate can be held with an appropriate holding force through a simple structure and can be carried in a short time. SOLUTION: The substrate carrier comprises a section 1 for containing a substrate W, a section 7 for holding the substrate W, a sensor section 5 for detecting at least presence of the substrate W in the containing section 1, a section G for detecting the weight at the substrate containing section 1, an operating means PC for calculating the weight of the substrate based on the outputs from the sensor section 5 and the weight detecting section G, and a control section PC for altering at least one of the holding force and the carrying characteristics at the holding section 7 based on the weight of the substrate W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a substrate transfer device, and more particularly to a substrate transfer device suitable for transferring a photosensitive substrate such as a wafer.

[0002]

2. Description of the Related Art Conventionally, when a wafer is transferred using a transfer device, for example, the wafer is always held at the same vacuum suction force and transferred at the same transfer speed and transfer acceleration regardless of the weight of the wafer.

[0003]

A conventional substrate transfer apparatus will be described with reference to FIGS. 3 and 4. FIG. In the conventional apparatus shown in FIG. 3, a wafer cassette 1 containing a plurality of wafers W is mounted on a wafer cassette mounting table 2. A part of the wafer cassette mounting table 2 is screwed with the feed screw 3. The rotating shaft of the motor 4 is directly connected to one end of the feed screw. Further, a mapping sensor 5 for detecting the presence / absence of the stored wafer W and its position is provided near the wafer take-out portion of the wafer cassette 1. The operator designates a wafer to be extracted from the wafer cassette 1 by operating a keyboard or the like (not shown).
A signal from a keyboard or the like is sent to the motor 4 via a computer. Then, the wafer mounting table is moved up and down to the designated height. Next, the wafer unloading arm 7 advances into the wafer cassette 1. Wafer cassette mounting table 2
Is lowered by a stroke corresponding to the amount by which the wafer W rides on the wafer take-out arm 7. The wafer take-out arm 7
It has holes for a plurality of suction pads 6 provided on the wafer take-out arm. Then, the wafer W is sucked to the wafer take-out arm 7 by applying a negative pressure to the hole of the suction pad 6.

[0004] Next, the wafer take-out arm 7
Is retracted in a direction away from the wafer cassette 1 while holding. Here, the suctioned wafer W can be transferred within a range where the product of the mass of the wafer and the acceleration / deceleration does not exceed the product of the suction force and the friction coefficient of the contact portion. After being inspected or processed, the wafer W transferred to the predetermined position is returned into the wafer cassette 1 in a procedure reverse to the procedure described above.

FIG. 4 is a diagram showing a schematic configuration of still another conventional substrate transfer apparatus. The same parts as those in FIG. 3 are denoted by the same reference numerals. 3 is different from the transfer device of FIG. 3 in that the wafer mounting table 2 moves up and down, whereas the transfer device of FIG. First, the wafer cassette 1 containing the wafer W is mounted on the wafer cassette mounting table 2. The motor 4 raises the position of the wafer take-out arm 7 by rotating the feed screw 3. At this time, the presence / absence and position of the wafer W are detected by the wafer sensor 5 provided on the wafer take-out arm 7. The operator specifies a wafer to be extracted from wafers existing in the wafer cassette by using a keyboard (not shown) or the like. By driving the motor 4, the wafer take-out arm 7 moves up and down to the designated take-out height of the wafer W. When the feed screw 8 is rotated by the motor 9, the wafer take-out arm 7 advances into the wafer cassette 1. Wafer take-out arm 7 is further raised by a stroke enough for wafer W to ride on wafer take-out arm 7. The wafer take-out arm 7 sucks the wafer W by applying a negative pressure to the hole of the suction pad 6 in the same manner as described above. Further, the wafer take-out arm 7 retreats while holding the wafer W.

Next, the wafer take-out arm 7
Is retracted in a direction away from the wafer cassette 1 while holding. Here, the suctioned wafer W can be transferred within a range where the product of the mass of the wafer and the acceleration / deceleration does not exceed the product of the suction force and the friction coefficient of the contact portion. After being inspected or processed, the wafer W transferred to the predetermined position is returned into the wafer cassette 1 in a procedure reverse to the procedure described above.

In such an apparatus of the prior art, the vacuum suction force, the transfer acceleration, and the like are set to constant values. The set value is the same when transferring a wafer lighter than a wafer having a transferable weight. For this reason, a light wafer can always be transferred at the same transfer acceleration, although it can be transferred at a higher acceleration than a heavy wafer. In other words, despite not being able to shorten the transport time, it has not been shortened.

In recent years, pattern miniaturization has progressed, and the pattern line width has been reduced. For this reason, in a wafer having a small thickness, a problem that the wafer is deformed by an external force and a pattern formed on the wafer is cut is likely to occur. As a result, the suction portion is likely to be deformed, and a problem such as breakage of the pattern printed on the wafer is likely to occur.) In the prior art apparatus, even when a lighter (thinner) wafer is transferred than a transferable weight wafer, the transfer is performed with the same suction force as when transferring a heavy wafer. For this reason, a thin (light) wafer has always been transported with the same suction force although it can be transported with a smaller suction force than a thick (heavy) wafer. In other words, although the suction force can be reduced, it is not reduced.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide a transfer apparatus capable of transferring a wafer in a short time and preventing a pattern from being cut even when a thin wafer is transferred. I do.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a substrate storage unit for storing a substrate, and a holding unit for holding and transporting the substrate stored in the substrate storage unit. A sensor unit for detecting the presence or absence of the substrate in the substrate storage unit; a weight detection unit for detecting the weight of the substrate storage unit; and a weight of the substrate based on outputs from the sensor unit and the weight detection unit. And a control unit that changes at least one of the holding force of the holding unit and the transfer characteristics based on the weight of the substrate.

Further, the present invention provides a substrate accommodating portion for accommodating a substrate, a holding portion for holding and transporting the substrate accommodated in the substrate accommodating portion, and determining whether the substrate is present in the substrate accommodating portion. A sensor unit for detecting, provided on the holding unit,
Provided is a substrate transfer device, comprising: a weight detection unit that detects the weight of the substrate; and a control unit that changes at least one of a holding force and a transfer characteristic of the holding unit based on the weight of the substrate. I do.

In a preferred embodiment, the holding force is desirably a vacuum suction force.

[0013] In a preferred aspect, the transfer characteristic is preferably a transfer acceleration.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a transfer device according to an embodiment of the present invention.

(First Embodiment) FIG. 1 is a diagram showing a configuration of a transport device according to a first embodiment. Multiple wafers W
Is mounted on a wafer cassette mounting table 2. A strain gauge G is provided on the wafer cassette mounting table 2. The wafer cassette mounting table is distorted by the sum M of the weight of the wafer cassette 1 and the total weight of each wafer W. The strain gauge G detects the distortion of the wafer cassette mounting table 2. The output signal from the strain gauge G is sent to the computer PC.

A part of the wafer cassette mounting table 2 is screwed with a feed screw 3. The rotating shaft of the motor 4 is directly connected to one end of the feed screw. Further, a mapping sensor 5 for detecting the presence / absence of the stored wafer W and its position is provided near the wafer take-out portion of the wafer cassette 1.

The signal from the mapping sensor 5 is sent to the computer PC, and the number n of wafers W stored in the wafer cassette 1 is stored. Therefore, the weight m per wafer is obtained by the following equation.

M = (M−Mc) / n (1) where Mc is the weight of the wafer cassette 1. Also,
The thickness t of the wafer W can also be calculated by the following equation.

T = (m / S) × C (2) where S is the area of the wafer and C is a constant.

Further, an appropriate vacuum suction force F for transferring a wafer having a thickness t is calculated by the following equation.

F = f (t) (3) where f is a function indicating the relationship between the vacuum suction force F and the thickness t.

Further, it is desirable that the vacuum suction force F, the coefficient of friction μ between the back surface of the wafer and the suction pad, and the transfer acceleration α when transferring a wafer having a weight m satisfy the following expressions.

F × μ> m × α (4) Accordingly, the maximum transfer acceleration αm for transferring a wafer having a weight of m
ax satisfies αmax <F × μ / m (5).

Returning again to the description of the transport procedure. The operator specifies a wafer to be extracted from the wafer cassette 1 by operating the keyboard KB. A signal from the keyboard KB is sent to the motor 4 via the computer PC. The motor 4 rotates the feed screw 3 to move the wafer mounting table 2 up and down to a designated height. Next, the wafer unloading arm 7 advances into the wafer cassette 1.
The wafer cassette mounting table 2 is lowered by a stroke corresponding to the amount by which the wafer W rides on the wafer take-out arm 7. The wafer take-out arm 7 has holes for a plurality of suction pads 6. The computer PC calculates the optimum vacuum suction force F based on the above equation (3). Then, the wafer W is sucked to the wafer take-out arm 7 by applying a negative pressure to the hole of the suction pad 6 so as to obtain the optimum vacuum suction force F.

Next, the wafer take-out arm 7
Is retracted in a direction away from the wafer cassette 1 while holding. Here, the computer PC uses the above equation (5).
Is calculated on the basis of the maximum transport acceleration αmax. Then, a drive signal is sent to the motor 9 so that the sucked wafer W is transferred at the transfer acceleration αmax. Thereafter, after a predetermined inspection step or processing step, the wafer is returned into the wafer cassette 1 by a procedure reverse to the procedure described above. As described above, the transfer apparatus according to the present embodiment can transfer the wafer W to the predetermined position with the optimal suction force and the minimum time.

(Second Embodiment) FIG. 2 is a view showing a configuration of a substrate transfer apparatus according to a second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals. 1 differs from the transfer apparatus of FIG. 1 in that the wafer mounting table 2 moves up and down, while the wafer transfer arm of the substrate transfer apparatus of FIG. 2 moves up and down. First, the wafer cassette 1 containing the wafer W is mounted on the wafer cassette mounting table 2. The motor 4 raises the position of the wafer take-out arm 7 by rotating the feed screw 3. At this time, the mapping sensor 5 provided on the wafer take-out arm 7 detects the presence or absence and the position of the wafer W, and sends a detection signal to the computer PC. The operator uses the keyboard KB to specify a wafer to be transferred among the wafers existing in the wafer cassette 1. The computer PC drives the motor 4 and rotates the feed screw 3 to move the wafer pick-up arm 7 up and down to a specified wafer W pick-up height. Next, by rotating the feed screw 8 by the motor 9, the wafer take-out arm 7 advances into the wafer cassette 1. The wafer take-out arm 7 further rises by the stroke amount at which the wafer W is placed on the wafer take-out arm 7.

The wafer take-out arm 7 is provided with a strain gauge G. The strain gauge G detects the amount of distortion of the wafer take-out arm 7 due to the weight of the wafer W and sends a signal to the computer PC. The computer PC calculates an appropriate vacuum suction force F based on the above equations (2) and (3). Then, similarly to the first embodiment, the wafer take-out arm 7 suctions the wafer W by setting the hole of the suction pad 6 to a negative pressure so as to obtain an appropriate vacuum suction force F.

The computer PC calculates the maximum transport acceleration αmax according to the above equation (5). And
The motor 9 is driven so that the wafer W is transferred at the transfer acceleration αmax.

Next, the wafer take-out arm 7
Is retracted in a direction away from the wafer cassette 1 while holding. Thereafter, after a predetermined inspection step or processing step, the wafer is returned into the wafer cassette 1 by a procedure reverse to the procedure described above. As described above, the transfer apparatus according to the present embodiment can transfer the wafer W to the predetermined position with the optimal suction force and the minimum time.

The transfer apparatus according to the present embodiment is applicable to, for example, a wafer inspection apparatus and a wafer exposure apparatus.

[0031]

As described above, according to the present invention, it is possible to change a holding force such as a vacuum suction force, a transfer acceleration, and the like according to the weight of each wafer. For this reason, the substrate can be transported in a short time without causing pattern cutting or the like.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a substrate transfer device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a substrate transfer device according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of a conventional substrate transfer device.

FIG. 4 is a diagram showing a configuration of another conventional substrate transfer apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wafer cassette 2 Wafer cassette mounting table 3, 8 Feed screw 4, 9 Motor 5 Mapping sensor 6 Suction pad 7 Wafer take-out arm W Wafer G Strain gauge

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5F031 CA02 DA01 FA01 FA07 FA11 GA08 GA36 GA48 GA49 JA01 JA06 JA12 JA22 JA43 JA45 JA51

Claims (4)

[Claims] 1. A substrate storage unit for storing a substrate, a holding unit for holding and transporting the substrate stored in the substrate storage unit, and a sensor unit for detecting the presence or absence of the substrate in the substrate storage unit A weight detection unit that detects the weight of the substrate storage unit; a calculation unit that calculates the weight of the substrate based on the outputs of the sensor unit and the weight detection unit; and the holding unit based on the weight of the substrate. And a control unit that changes at least one of a holding force of the unit and a transfer characteristic. 2. A substrate storage unit for storing a substrate, a holding unit for holding and transporting the substrate stored in the substrate storage unit, and a sensor unit for detecting the presence or absence of the substrate in the substrate storage unit. And a control unit that is provided in the holding unit and detects a weight of the substrate, and a control unit that changes at least one of a holding force and a transfer characteristic of the holding unit based on the weight of the substrate. A substrate transfer device characterized by the above-mentioned. 3. The substrate transfer device according to claim 1, wherein the holding force is a vacuum suction force. 4. The substrate transfer apparatus according to claim 1, wherein the transfer characteristic is a transfer acceleration.